What sub size? [Archive] - Audio & Video Forums


View Full Version : What sub size?

07-17-2006, 02:00 PM
Hey, not sure which area this question should go so I'm just putting it here.

I recently bought a Yamaha RX-V2500 HT receiver hooked up my 'first phase' of speakers: 2 front towers. My second phase is to get a sub so I can get those great low rumbles I've always been deprived. While looking in local ad fliers for subs, I realized that I don't know how many Watts power my V2500 will send to the sub. I know it is 7.1 and each speaker gets 130watts, but it doesn't specify what the sub gets. I looked in the manual and it doesn't specify. I'd really love to get as powerful of a sub as I can, but if I get a 500 Watt sub and all it puts out is 300 watts, well that's a waste of my money, and if I buy a 300 watt and it can put out 500 watts, well that's a waist of watts. So does anyone here know how to figure out what wattage my sub can be? Is there a general rule of thumb?

07-17-2006, 02:55 PM
There's no rule of thumb with subs because the amount of output that you need will depend on so many different factors. The name of the game is moving air, and doing so with relatively decent accuracy. A large 15" cone has more surface area and might not need much wattage at all to move a massive amount of air, whereas a smaller 8" cone will need to produce a lot more movement to equal the amount of air that a larger cone can move and to do so might require more wattage. Even here, the designs and efficiencies of the drivers will vary a lot, and many of them will bottom out before the amp reaches peak load anyway.

However, these points are totally moot if you have a relatively small room, in which case the boundary gain effect that your room produces will potentially negate any need for a lot of wattage. You can get a massive headache well before reaching the peak limits from either the amp or driver. Your bigger concern will be with taming the room induced peaking and trying to get the bass listenable in the first place.

In addition, the box configuration will also dictate how powerful an amp you'll need. In general, ported subs are more efficient and can produce higher peak SPLs than sealed subs, while bandpass subs are even more efficient. Each of these designs have tradeoffs with the bass quantity and bass quality.

In choosing a sub, you need to consider how large a room you have to fill, and then identify the kind of bass that you're looking for. Do you want maximum decibel peak levels? Do you plan to listen to more music than movies? The wattage in the subwoofer amplifier is down the list of considerations that you should worry about. In general, I would say that how you set up the subwoofer (i.e. setting the crossover point, positioning it within the room, setting the levels, etc.) and how you deal with acoustical issues in your room is every bit as important, if not more, as which subwoofer you choose to go with. I use a parametric equalizer with my subwoofer to address the room issues in my setup, and I can safely say that the bass quality I get on my system is better than nearly all of the unequalized subs that I've heard over the years.

07-17-2006, 04:48 PM
Your receiver doesn't amplifiy the sub, it merely sends it the audio signal. That means you need to buy a powered sub, one that has a built in amplifier. Now, I don't know as much about such matters as does Woochifer, but I can tell you that quality subs begin at around $500 on up to ungodly amounts of money. Look into reputable brands, as non-specializing manufacturers can make such crappy subs that it's not even worth having. Check into Velodyne, Hsu, SVS (the latter two online only), Definitive Tech, Paradigm, B&W, etc.

07-18-2006, 02:30 PM
Wow, Thank you both for the info. Most of it flew over my head. I guess there's much much more to this then I thought. I'd be using it mainly for music. My room is well, I live in an apartment style condo, so my room shaped (for the most part) in the shape of an L.

With this info I'll start looking for more details and hopefully be able to go from there without pestering anyone here more then I would normally :)

07-20-2006, 12:30 PM
Apartment style condo?

You should probably get a 1,000 watt sub. This will save a lot of time arguing with the neighbors. Instead of arguing, they will probably bring a gun and resolve the issue on the first visit.:cornut: